DESCRIPTION: The primary goal of this project is to investigate the components contributing to the three-dimensional structure of the ocular zonule. The relation of proteins known to be associated with microfibrils like those in the zonule will be studied during their synthesis by bovine lens ciliary epithelial cells and dermal fibroblasts in culture, using immunoelectron microscopy, rotary shadowing and deep-etch freeze fracture methods. The culture matrices will be examined for binding of the associated proteins to cells, individual microfibrils or aggregated fibrils. To further define the roles of the associated proteins their function will be inhibited by specific antibodies to determine the effect on microfibril structure and aggregation. Evidence for lysyl oxidase and transglutaminase-mediated lysine cross-linkages contributing to stability of the zonular bundles will be examined by the same methods. In fetal and older vertebrate eyes, in situ hybridization will be used to test for expression of fibrillin-1 mRNA, the main protein component of zonular microfibrils. Defining the period of active zonulogenesis will aid in studying regulation of this process. Specific adhesion mechanisms for attaching the zonular fibers to basement membranes on the lens and ciliary body will be investigated, particularly the role of RGD sequences in fibrillin and many of the microfibril-associated proteins. These studies are directed toward understanding the defects which underlie the hereditary and other diseases affecting the ocular zonule, causing fragility and breakage of the microfibrils and resulting in dislocation of the ocular lens. The pseudoexfoliation syndrome, one of the lens-dislocating diseases which is an important cause of glaucoma in the elderly will be a prime focus of this investigation, to characterize the zonular abnormalities in this disease. Genetic studies will also be carried out on the patients.